1. Field of the Invention
This invention relates to a wafer cleaning method in a manufacturing stage for a semiconductor device, and more particularly a technology for removing particles left on the wafer surface within a vacuum environment after processing with plasma or after flattening with plasma at a pre-stage of the semiconductor manufacturing process.
2. Description of the Related Prior Art
In the prior art cleaning for a semiconductor wafer (hereinafter abbreviated as a wafer), the cleaning operation is carried out such that either pure water or a solution diluted with various kinds of acids or an alkaline solution is applied. The wafer is immersed in the solution or the solution is blown against the wafer to wash away particles at the surface of the wafer. In addition, a method for mechanically cleaning the wafer surface with a brush concurrently with immersion of wafer in the solution or the like is also used.
The aforesaid cleaning method of the prior art shows the following problems due to the fact that this is a so-called wet cleaning method in which basically water is used for cleaning operation.
1) Although a continuous total processing within a vacuum environment such as a dry etching or a plasma CVD or the like increases a machining precision or manufacturing efficiency, cleaning operation required after each of the processings is a wet type processing, so that it generates a necessity for once putting out the wafer into atmosphere and thus the aforesaid effects may not be attained.
2) The wet cleaning operation requires a rinsing stage and a drying stage in addition to the cleaning operation, resulting in that the number of manufacturing stages is increased.
3) In the case of wet cleaning operation, the pole surface of the semiconductor material is degraded in its quality and as the size of a semiconductor device is made small, its yield is reduced by the degraded material quality at the surface.
4) In the case of performing the wet cleaning operation, liquid is not sufficiently immersed on the small structural part of the semiconductor device sometimes due to a surface tension of liquid and suitable cleaning power with respect to the small structural part is insufficient.
5) A high performance device has required high wet-absorbing material such as organic film or porous organic film as a new material for a semiconductor device, and, in particular, an insulating film material as a new material in the future. In the case of manufacturing the semiconductor device using these new materials, either the wet cleaning or a mere occasional exposure in the surrounding atmosphere causes a characteristic of the device to be deteriorated.
6) A wet cleaning is normally carried out under a batch processing. In the case that the wafer has 300 mmxe2x88x85 (diameter) or more, it takes much time in cleaning of the wafer and handling before and after the cleaning.
In turn, as a cleaning method in place of the aforesaid wet cleaning operation, there is provided a dry cleaning method. As to the dry cleaning method, this method has been disclosed in Japanese Patent Laid-Open Nos. Hei 8-131981, 8-85887 or 9-17776, for example.
It is an object of the present invention to provide a cleaning method performed in vacuum and a dry cleaning method capable of attaining a cleaning power corresponding to the wet processing even in cleaning within vacuum environment in order to solve the problems accompanied with the aforesaid wet cleaning.
A summary of the disclosed invention that is a representative one of the disclosed inventions will be described in brief as follows.
The dry cleaning method of the present invention is characterized in that the front surface and/or the rear surface of the wafer are cleaned by a method wherein pads or blocks arranged near or in contact with the front surface and the rear surface of the processed wafer within a processing container vacuum evacuated by a vacuum evacuating means and each of the pads is moved relative to the wafer while a gas flow is being supplied between the pads and the wafer.